Toolholder and Toolholder Assembly with Elongated Seating pads

ABSTRACT

A toolholder has a pocket adapted to receive a double-sided on-edge cutting insert, wherein the corners of each side of the insert are radially shifted with respect to one another and has mounting pads preferably mounted about the sides of the cutting insert. The relief area for the corners of the insert is selectively fabricated to maximize the length of the support pads within the pocket of the toolholder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to toolholders for metal working operations and,more specifically, to a toolholder having a pocket with elongatedseating pads for accommodating matching seating pads of a cutting insertmounted within the pocket.

2. Description of Related Art

A goal of most metal working operations is to perform a given machiningtask in the least amount of time and in a manner that will not result inpremature tool failure. In particular, in a milling operation usingon-edge cutting inserts within pockets of a milling cutter, it isnecessary to securely mount these inserts within the pockets. Typically,such on-edge inserts include side surfaces which contact seating padswithin the pocket for support. However, as illustrated in U.S. Pat. No.3,490,117, which illustrates on-edge cutting inserts mounted within thepockets of a toolholder, a unique problem arises. To provide areversible cutting insert with multiple cutting edges, for a singlecorner the cutting edges on one side of the insert are angularly shiftedrelative to those cutting edges on the other side. This creates cornerswith offset cutting edges and the pocket of the toolholder must beformed to provide clearance for these corners. While this providesadequate clearance for the corners of the cutting insert, this comes atthe sacrifice of shortening the seating surfaces in the toolholderpocket, thereby providing less support to the cutting insert that may beavailable otherwise.

A design is needed for accommodating such on-edge inserts withoutsacrificing the length of the seating surfaces in the pocket of thetoolholder.

SUMMARY OF THE INVENTION

One embodiment of the invention is directed to a toolholder for use in ametalworking operation, wherein the toolholder is adapted to hold anon-edge cutting insert with a depth and having first and second opposingsegments about a central plane and with a central axis therethrough.Each segment of the insert has at least three sides and associatedcorners defining end cutting edges and, wherein each segment is radiallyoffset relative to the other. The toolholder has a body extending alonga longitudinal axis and having a first end and a pocket extending intothe first end, wherein the pocket has at least two sides and the generalshape and depth of the cutting insert intended to be held therein and,wherein the at least two sides intersect to define a pocket corner. Thepocket has a primary deep relief area located within the pocket cornerand associated with a segment corner of the first segment and, whereinthe primary deep relief area extends substantially to the depth of thecutting insert intended to be held within the pocket. The pocket alsohas a primary shallow relief area located within the same pocket cornerand associated with a segment corner of the second segment and, whereinthe primary shallow relief area is adapted to accommodate only thesegment corner of the second segment and, wherein the primary shallowrelief area extends only to the depth of the second segment. Supportpads extend from each of the at least two sides of the pocket defining athird segment between the first and second segments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a toolholder in accordance with thesubject invention with cutting inserts mounted therein;

FIG. 2 is a side view of a cutting insert that may be mounted within thepocket of the toolholder;

FIG. 2B is an enlargement of the area encircled in FIG. 2 labeled 60;

FIG. 3 is an exploded view showing the manner by which a cutting insertmay be mounted within a toolholder pocket;

FIG. 4 is a portion of the toolholder illustrating the toolholder pocketviewed along an axis perpendicular to the pocket floor;

FIG. 5 is a view of the toolholder pocket when viewed along line 5 inFIG.4;

FIG. 6 is a view similar to that illustrated in FIG. 4, but with across-sectional portion of a cutting insert mounted within the pocket toillustrate clearances on the lower half of the insert;

FIG. 7 is a view similar to FIG. 4, however, now including a full insertwithin the pocket again illustrating the clearances around the cornersof the cutting inserts;

FIG. 8 is a milling cutter in accordance with another embodiment of theinvention, whereby the surface of a seating pad within a pocket has agap along its length; and

FIG. 9 is a perspective view of a cutting insert identical to thatillustrated in FIG. 3, with the exception of split mounting surfaces.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a toolholder 10 having a body 12 extending along alongitudinal axis 15 and having a first end 17. A plurality of pockets20 extend about the perimeter of the toolholder body 12 and mountedwithin each of these pockets 20 is a cutting insert 25. The cuttinginsert 25 is an on-edge cutting insert, whereby the major cutting edgesare located on the ends 27, as opposed to the sides 30 of the cuttinginsert 25. For on-edge cutting inserts, the surface area of each side issignificantly greater than the surface area of any one of the ends 27.

Although some milling cutters may have different types of cuttinginserts mounted within different pockets, for the purposes of discussionand as illustrated herein, all of the cutting inserts 25 are identicaland the pockets 20 are identical, such that only a single cutting insert25 and single pocket 20 will be discussed with the understanding thatthe others are identical.

Directing attention to FIG. 3, a typical on-edge cutting insert 25 thatmay be used in the subject toolholder 10, has a depth D and has a firstsegment 35 and a second opposing segment 45 about a central plane 55,with a central axis 57 extending therethrough. In particular, if theinsert 25 was cut in half along the central plane 55 and segment 45 wasflipped and placed next to segment 35, the two segments would appear tobe identical. For discussion, common corner A has been marked in FIGS.1-3. As illustrated in FIGS. 2 and 3, the first segment 35, which may beenvisioned as the lower segment, has four sides 37 a, 37 b, 37 c, 37 d(FIG. 2) and associated corners 39 a, 39 b, 39 c, 39 d defining endcutting edges 40 a, 40 b, 40 c, 40 d. For assistance in identifyingthese surfaces, the reference numbers for each side have been used intwo locations. Correspondingly, the second segment 45, which may beenvisioned as the upper segment, has four sides 47 a, 47 b, 47 c, 47 dand associated corners 49 a, 49 b, 49 c, 49 d defining end cutting edges50 a, 50 b, 50 c, 50 d.

As can be seen in FIG. 2, the first segment 35 is radially offset aboutthe central axis 57 relative to the second segment 45 by an angle X. Xmay be in the range of 1 to 4 degrees and, as illustrated herein, isapproximately 2.5 degrees.

Directing attention to the encircled area identified as 60 and enlargedin FIG. 2B, a key feature of the subject invention is the manner bywhich the toolholder accommodates the corner 39 a of the first segment35 and the corner 49 a of the second segment 45, which are offset fromone another.

As illustrated in FIG. 3, the first segment 35 of the cutting insert 25has a depth D/2 which is half the overall depth D. The second segment 45also has a depth D/2 which is half the overall depth D.

The insert 25 is supported within the pocket 20 at three locations. Thisfirst surface is a flat surface, identical to flat surface 64, but onthe opposite side of the insert, which rests against the floor 70 of thepocket 20. Additionally, there are four mounting surfaces 75 a, 75 b, 75c, 75 d on the cutting insert 25 suitable for mounting against supportpads 78, 80 extending from the first side 82 and the second side 84 ofthe pocket 20 to provide the other two surfaces. The support pad 80 mayalso be referred to as the axial support pad because it supports loadsalong the longitudinal axis 15 of the milling cutter 10. Additionally,support pad 78 may be referred to as the tangential support pad becauseit supports loads tangential to the longitudinal axis 15. The mountingsurfaces 75 a, 75 b, 75 c, 75 d of the cutting insert 25 define a thirdsegment 76 situated between the first segment 35 and the second segment45.

The pocket 70 has the general shape and depth of the cutting insert 25intended to be held therein and the two sides 78, 80 intersect to definea pocket corner 86. As discussed, the support surfaces in the pocket 20for the insert 25 are the pocket floor 70, the support pad 78, and thesupport pad 80. The majority of the force produced during a machiningoperation when the toolholder is a milling cutter illustrated in FIG. 1is transmitted through the corner 49 c to the support pad 78 andsecondary forces are transmitted to the support pad 80.

It should be noted that there is a threaded bore 88 (FIG. 3) within thefloor 70 of the pocket 20 to accept a retaining insert screw (not shown)which passes through the central bore 90 of the insert 25. In general,the insert screw is intended to locate the insert 25 within the pocket20 and is not intended to absorb significant forces caused by themetalworking operation. As a result, the large majority of the forcesproduced during the cutting operation are applied to the support pads78, 80 and, it is very important that each of these support pads 78, 80contact the associated mounting surface 75 a, 75 b on the insert 25 withas much surface area as possible. Worded differently, it is importantfor the two support pads 78, 80 to be as long as possible, while at thesame time providing the necessary clearance to the insert corners, suchas corners 39 a and 49 a, of the cutting insert 35.

Directing attention to FIG. 3, in order for the cutting insert 25 to bemounted within the pocket and for the support pad 78 and support pad 80to engage the appropriate mounting surface 75 a, 75 b of the cuttinginsert 25, it is necessary for the pocket 20 to include relief areas forthe corners (50 a shown) of the cutting insert 25. One corner 86 hasalready been identified. FIG. 2B illustrates the portion of the cuttinginsert 25 that will rest within the corner 86 of the pocket 20.

Because the corner 39 a of the first segment 35 resides only in thelower half of the cutting insert, and corner 49 a of the second segment45 resides only in the upper half of the cutting insert 25, asillustrated in FIG. 3, then the corner 86 of the toolholder 20 may besculpted to conform to this unique corner profile of the insert withminimum impact to the length of the support pad 80. In particular, aprimary deep relief area 100 is located within the pocket corner 86 andis associated with the segment corner 39 a (FIG. 2B) of the firstsegment 35 and extends substantially to the depth D of the cuttinginsert 25. This is also illustrated in FIG. 6. Significantly, ratherthan enlarging the primary deep relief area 100 to accommodate thecorner 49 a (FIG. 2B) of segment 45, a primary shallow relief area 110is located within the same pocket corner 86 and is associated withcorner 49 a. This is also illustrated in FIG. 7. This primary shallowrelief area 110 is sculpted to accommodate only the corner 49 a of thesecond segment 45 and extends only to the depth of corner 49 a, which,as illustrated in FIG. 3, is one-half the depth of the entire insert 25.

In such a fashion, the length of the second support pad 80 is maximized,while at the same time, the relief area 110 is provided for the corner49 a. It should be appreciated that the depth of the primary shallowrelief area 110 extends only to the support pad 80 to maximize thelength of the support pad 80. Without such an accommodation, the primaryshallow relief area 110 would extend the entire depth of the pocket 20and remove the portion of the support pad directly below the primaryshallow relief area 110.

As a result, the corner 86 has a dual relief area that has a primarydeep relief area 100 extending substantially the entire depth of theinsert 25 and a primary shallow relief area 110, adjacent to the primarydeep relief area 100 that extends to a partial dept of the insert 25.

Directing attention to FIG. 3, each support pad 78, 80 extends along thelength and protrudes from its respective side 82, 84 of the pocket 20 todefine recesses 104 a, 104 b, 106 a, 106 b adjacent to the pads 78, 80to provide additional clearance to the cutting insert 25.

Directing attention to FIG. 4, the primary shallow relief area 110overlaps the support pad 80 by a distance N, which is approximately 10to 20 percent of the length L of the support pad 80. In a preferredembodiment, the primary shallow relief area 110 overlaps the support pad80 over approximately 15 percent of the length L of the support pad 80.

As illustrated in FIG. 4, the length L of the support pad 80 extendsbeyond the primary shallow relief area 110 to the primary deep reliefarea 100. The primary deep relief area 100 is a generally cylindricalbore 102 extending into the body 12 of the toolholder 10 and may besimply manufactured utilizing a drill. On the other hand, the primaryshallow relief area 110 has an extended shape and may be manufacturedusing an end mill.

Briefly returning to FIG. 2, the first segment 35 and the second segment45 are angularly offset with respect to one another but, furthermore,are angularly offset with respect to the third segment 76 as measuredfrom an associated mounting surface 75 c by an angle X/2.

As illustrated herein, the pocket 20 has two walls 78, 80 to accommodatea cutting insert 25 having four walls. It should be appreciated that thesubject invention is not limited to a cutting insert having four sidesbut may also accommodate, with appropriate modifications, inserts havingat least three sides.

While what has so far been discussed is accommodating within the pocket20 corner 37 a of first segment 35 and corner 49 a of second segment 45,the subject toolholder design may also accommodate two additional pairsof insert corners. In particular and focusing upon FIGS. 3 and 4, asecondary deep relief area 120 extends within the pocket 20 adjacent tothe support pad 80 opposite the pocket corner 86. The secondary deeprelief area 120 extends substantially the entire depth D of the cuttinginsert 25 intended to be held within the pocket 20.

Additionally, a secondary shallow relief area 130 extends within thetoolholder 10 adjacent to the support pad 78 opposite the pocket corner86. The secondary shallow relief area 130 extends only to the depth D/2of the second segment 45.

The secondary shallow relief area 130 overlaps the support pad 78 adistance N′, which is approximately 10 to 20 percent of the length L′ ofthe support pad 78. Preferably, the secondary shallow relief area 130overlaps by approximately 15 percent.

FIG. 5 is an end view of a portion of the milling cutter 10 lookingupwardly into a pocket 20 from the first end 17, illustrated in FIG. 1.Support pad 80 is illustrated as generally perpendicular to support pad82 and the pocket floor 20 has the threaded bore 88 extendingtherethrough. Recess 104 a and recess 104 b along with recesses 106 aand 106 b are visible. The depth of the primary deep relief area 100with respect to the depth of the primary shallow relief area 110 may bebetter appreciated from this view.

FIG. 6 illustrates a view similar to that of FIG. 4 but with the cuttinginsert 25 mounted within the pocket 20. FIG. 6 also illustrates a crosssection of the cutting insert 25 along plane 55 shown in FIG. 3. As aresult, only the first segment 35 of cutting insert 25 is illustrated.Of particular interest, corner 39 a of segment 35 of the cutting insert25 is provided adequate clearance by the primary deep relief area 100.

Directing attention to FIG. 7, the entire cutting insert 25 isillustrated within the pocket 20 and it becomes apparent that the corner49 a of side 47 a could not be accommodated by the primary deep reliefarea 100 only and additional relief area is required. It is for thisreason the primary shallow relief area 110 exists and, furthermore, thatthe depth of the primary shallow relief area 110 extends down to theside of the support pad 80, as illustrated in FIG. 3.

The toolholder 10 has been discussed with respect to a milling cutter,however, it should be appreciated that the design discussed herein maybe easily adapted to the pocket of a stationary toolholder used forturning applications.

Discussed so far, the mounting surfaces 75 a, 75 b, 75 c, 75 d, whichare generally planar, have been designed to contact the respectivesupport pads 78, 80 while the flat surface 64 (opposite side) has beendesigned to contact the floor 70 of the pocket 20. Due to manufacturingtolerances, full contact between the respective mounting surfaces 75 a,75 b, 75 c, 75 d and the support pads 78, 80 is difficult to achieve.Therefore, another embodiment of the subject invention is directed to adesign that will provide three-point contact between the support pads78, 80 and the respective mounting surfaces 75 a, 75 b, 75 c, 75 d onthe sides 47 a, 47 b, 47 c, 47 d of the insert 25. In particular anddirecting attention to FIG. 8, a support pad 180 perpendicular to thelongitudinal axis 15, has an indentation 182 between the two ends 184,185 of the support pad 180. The location of the indentation 182 may becentrally located between the two ends 184, 185. However, the primarypurpose of the indentation 182 is to force contact at the support padportions 187, 189 now defined by the indentation 182. By doing so, theassociated mounting surface 75 a, 75 b, 75 c, 75 d (FIG. 3) of thecutting insert 25 will be supported at two predetermined locations onsupport pad 180. Additionally, the support pad 190 parallel to thelongitudinal axis 15, has an indentation 192 that extends along asignificant portion of the pad 190 beyond the single support pad portion197 that remains elevated. In such a fashion, the support pad 180 andthe support pad 190 provide a three-point contact to the mountingsurfaces 75 a, 75 b, 75 c, 75 d of the cutting insert 25.

FIG. 9 illustrates a different embodiment of the cutting insert 225,wherein the mounting surfaces 275 a, 275 b, 275 c, 275 d are split. Inparticular, with respect to mounting surface 275 c, which isrepresentative of all of the mounting surfaces 275 a, 275 b, 275 c, 275d, there is a mounting surface portion 277 c, another mounting surfaceportion 279 c and an indentation 281c, therebetween. By providing anindentation 281c between the mounting surfaces 277 c, 279 c, the contactbetween the mounting surface 275 c of the cutting insert 225 and theassociated support pad 78, 80 (FIG. 3) of the pocket 20 will occur atthe mounting surfaces 277 c, 279 c. Note that, in actuality, mountingsurfaces 275 a and 275 b would contact support pads 78, 80, however,mounting surface 275 c is discussed because it is visible. Thisminimizes the likelihood of uneven surface contact between the cuttinginsert 225 and the pocket 20 that may cause the insert 225 to rockwithin the pocket 20.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. The presentlypreferred embodiments described herein are meant to be illustrative onlyand not limiting as to the scope of the invention which is to be giventhe full breadth of the appended claims and any and all equivalentsthereof.

1. A toolholder for use in a metalworking operation, wherein thetoolholder is adapted to hold an on-edge cutting insert with a depth andhaving first and second opposing segments about a central plane and witha central axis therethrough, wherein each segment has at least threesides and associated corners defining end cutting edges and, whereineach segment is radially offset relative to the other, wherein thetoolholder comprises: a) a body extending along a longitudinal axis andhaving a first end; b) a pocket extending into the first end, whereinthe pocket has at least two sides and the general shape and depth of thecutting insert intended to be held therein and, wherein the at least twosides intersect to define a pocket corner; c) a primary deep relief arealocated within the pocket corner and associated with a segment corner ofthe first segment and, wherein the primary deep relief area extendssubstantially to the depth of the cutting insert intended to be heldwithin the pocket; d) a primary shallow relief area located within thesame pocket corner and associated with a segment corner of the secondsegment and, wherein the primary shallow relief area is adapted toaccommodate only the segment corner of the second segment and, whereinthe primary shallow relief area extends only to the depth of the secondsegment; and e) supports pads extending from each of the at least twosides of the pocket defining a third segment between the first andsecond segments.
 2. The toolholder in accordance with claim 1, eachsupport pad extends along the length and protrudes from a side to definerecesses adjacent to the pads for providing clearance to the cuttinginsert segments.
 3. The toolholder in accordance with claim 1, whereinthe depth of the primary shallow relief area extends to the support pad.4. The toolholder in accordance with claim 1, wherein the primaryshallow relief area is shaped to accommodate, in conjunction with theprimary deep relief area, the second segment corner.
 5. The toolholderin accordance with claim 1, wherein the primary shallow relief areaoverlaps the support pad over approximately 10-20 percent of the lengthof the support pad.
 6. The toolholder in accordance with claim 5,wherein the secondary shallow relief area overlaps the support pad overapproximately 15 percent of the length of the support pad.
 7. Thetoolholder in accordance with claim 1, wherein the length of the supportpad extends beyond the primary shallow relief area to the primary deeprelief area.
 8. The toolholder in accordance with claim 1, wherein theprimary deep relief area is a generally cylindrical bore extending intothe toolholder body.
 9. The toolholder in accordance with claim 1,wherein the first and second segments are radially offset with respectto the third segment by an angle of between 1-4 degrees
 10. Thetoolholder in accordance with claim 9, wherein the first and secondsegments are radially offset with respect to the third segment by anangle of between 2.5 degrees.
 11. The toolholder in accordance withclaim 1, wherein the pocket has two walls to accommodate a cuttinginsert having four sides.
 12. The toolholder in accordance with claim 1,further including a secondary deep relief area along the support padopposite the primary shallow relief area, wherein the secondary deeprelief area extends substantially the entire depth of a cutting insertintended to be held within the pocket.
 13. The toolholder in accordancewith claim 12, further including a secondary shallow relief area alongthe support pad opposite the end of the primary deep relief area,wherein the secondary shallow relief area extends only to the depth ofthe second segment.
 14. The toolholder in accordance with claim 13,wherein the secondary shallow relief area overlaps the support pad overapproximately 10-20 percent of the length of the support pad.
 15. Thetoolholder in accordance with claim 14, wherein the secondary shallowrelief area overlaps the support pad over approximately 15 percent ofthe length of the support pad.
 16. The toolholder in accordance withclaim 1, wherein the support pad perpendicular to the longitudinal axishas an indentation between the two ends, such that the two ends providesupport to the cutting insert.
 17. The toolholder in accordance withclaim 16, wherein a support pad perpendicular to the longitudinal axishas an indentation centrally located between the two ends.
 18. Thetoolholder in accordance with claim 17, wherein a support pad parallelto the longitudinal axis has an indentation at the end closest to thepocket corner, thereby providing a three point contact to a cuttinginsert secured within the pocket.
 19. The toolholder in accordance withclaim 1, further including a threaded bore extending within the pocketfloor to receive a mounting screw for holding the cutting insert withinthe pocket.
 20. The toolholder in accordance with claim 2, wherein thetoolholder is a milling cutter.
 21. A toolholder for use in ametalworking operation, wherein the toolholder comprises: a) a bodyhaving a first end, wherein the body extends along a longitudinal axis;b) a pocket extending into the first end, wherein the pocket has thegeneral shape and depth of an on-edge cutting insert intended to be heldtherein and, wherein the pocket has a pocket floor and at least a firstinterior wall and a second interior wall extending upwardly from thepocket floor; c) wherein the first and second interior walls intersectto form a corner region and, wherein the corner region has a dual reliefarea extending into the depth of the pocket to provide relief for acorner of a cutting insert mounted therein and having two radiallyshifted cutting edges; d) wherein the dual relief area has a firstrelief area that extends substantially the entire depth of the insertand a second relief area adjacent to the first relief area that extendsto a partial depth of the insert; and e) a third segment between thefirst and second segments, wherein the third segment has sidescorresponding to the first and second segment sides, wherein the firstand second segments are radially offset relative to the third segmentsuch and, wherein the sides define support pads adapted to engagematching mounting surfaces on the cutting insert.
 22. The toolholder inaccordance with claim 2, wherein the toolholder is a milling cutter. 23.A toolholder assembly for use in a metalworking operation, wherein theassembly comprises: a) an on-edge cutting insert with a depth and havingfirst and second opposing segments about a central plane and with acentral axis therethrough, wherein each segment has at least three sidesand associated corners defining cutting edges and, wherein each segmentis radially offset relative to the other, b) a body extending along alongitudinal axis and having a first end; c) a pocket extending into thefirst end, wherein the pocket has at least two sides and the generalshape and depth of the cutting insert intended to be held therein and,wherein the at least two sides intersect to define a pocket corner; d) aprimary deep relief area located within the pocket corner and associatedwith a segment corner of the first segment and, wherein the primary deeprelief area extends substantially to the depth of the cutting insertintended to be held within the pocket; e) a primary shallow relief arealocated within the same pocket corner and associated with a segmentcorner of the second segment and, wherein the second relief area isadapted to accommodate only the segment corner of the second segmentand, wherein the second relief area extends only to the depth of thesecond segment; and f) supports pads extending from each of the at leasttwo sides of the pocket defining a third segment between the first andsecond segments.
 24. The toolholder assembly in accordance with claim23, wherein the toolholder support pads have indentations to providecontact with a cutting insert at known locations.
 25. The toolholderassembly in accordance with claim 23, wherein the cutting insertmounting surfaces have indentations to provide contact with the pocketof the toolholder at known location.